The present invention relates to a new and improved primary surface for use in a corrugated plate type heat exchanger, and more particularly a heat exchanger device made up of a plurality of plates of relatively thin material, so formed and stacked as to provide heat transfer through the plates to and from a series of alternate flow passages formed between the stacked, alternate plates.
U.S. Pat. No. 3,424,240 to Stein et al., assigned to the assignee of the present invention, discloses a heat exchanger device made up of a plurality of plates formed in two types of configurations stacked alternately in pairs to form the stack. The two types of plates have spaced openings therethrough which are aligned when stacked to form inlets and outlets to and from one of the series of longitudinal flow passages in the stacked plates. The first type of plates is preferrably formed with a pattern of corrugations between the spaced openings extending across the plates in a radially outward direction thus providing channel forming, generally parallel wave formations on both surfaces thereof. On the other hand, the other of the two types of plates is formed with a pattern of generally parallel corrugations extending circumferentially along the plates between the spaced openings therethrough, the pattern of corrugations on the second type of plates extending transversely to the corrugations provided on the first type of plates when the two different types of plates are positioned adjacent one another to form a construction pair with the spaced openings in alignment. The aligned openings in the first and second types of plates are sealed together by welding or brazing.
When the first and second types of plates are placed adjacent each other, a grid of touching points is formed between each pair of adjacent plates by the intersection of the longitudinal and transverse ridges from the alternate plates. A plurality of flow passages through which a gas or air travels are established between the touching points on the grid. When so formed, however, a contraction and expansion of the flow passage at each transverse ridge is inherently produced, the flow passages varying in area along the direction of flow to thereby promote thermal mixing within the passages and enhance the rate of heat transfer.
However, by reducing the pressure losses associated with expanding and contracting passages, a primary surface heat exchanger may achieve a higher ratio of heat transfer parameter to friction factor.